PMP-128 Modular reed-switch level sensor

Reed switch. Modular. Measurement of level, media interface level, temperature, density, volume and weight calculation. Measuring range - up to 25 m.


Applied for measurement and control of level, media interface level, temperature, definition of density, volume and weight of liquid non-crystallizing media (including petroleum products and LPG) on sites of oil and gas, chemical, automotive, ship building, water processing, municipal, foodstuff and other industries.

Applied in process systems for:

  • signaling of critical values reaching for the measured parameters
  • automated accounting of liquid products (commercial application)
  • prevention of idle work of the pumping stations
  • automatic adjustment of level and temperature
  • prevention of tanks overfilling

Main operation sites: oil depots (equipment of vertical tanks), gas and oil storages, oil filling terminals, process systems of oil development and refining, etc.


  • absence of blind spots of level measurement in places of probes connection
  • modular design for easy transportation, installation and maintenance
  • level measurement range up to 25 meters
  • transmits processed values of measured parameters
  • simple integration into various telematics systems
  • shock-resistant housing made of aluminum alloy or corrosion-proof steel
  • explosion-proof modification
  • easy operation and commissioning
  • transit connection
  • continuous self-testing
  • various types of mounting devices for protective cable sheath (metal hose conduit, armored cable, pipe)


The transducer consists of separate parts connected by the thread: housing, connector, measuring probes, plug with clamp. The guide pipe, which is formed by the probes and connectors, contains a float with two magnets.

Length of each probe and their quantity are selected on the basis of tank height. Connectors (hollow tubes) are used to increase the length of the guide pipe at the top of tank.

The principle of liquid level measurement is based on the effects of magnets, located at the bottom and top float part, on contacts switches (magnetic sensitive reed) located inside the probes: the float moves along the guide together with the liquid level and causes closure of reed switches by its magnet.

The continuity of measurement with 5 mm step is reached by installation of reed switches in a row and connection of them to resistors using the diagram of a resistive voltage divider with its circuits connected to the controller.

One or two floats may be used in the transducer. Second float is used for measurement of media interface level (produced water).

Measurement of product temperature is made by integrated temperature sensors which are placed in the middle of each probe below the float level.

Apart from level of liquid, media interface and temperature, the converter may be used to define density, volume and weight of product.

Calculation of volume, density and weight of petroleum products and LPG are carried out in accordance with data specified in the standards: GOST 26976-86 "Oil and petroleum products.Methods of weight measurement"; GOST R 8.5952002 "Weight of oil and petroleum products. General requirements for measurements execution methods"; GOST 28656-90 "Liquified hydrocarbon gases. Calculation method for determination of density and pressure for saturated vapors".